Resonant reed relay



April 10, 1962 A. N. FISCHER RESONANT REED RELAY Filed Oct. 22, 1959FIG. I

l I 15 17 I7 .III

FIG. 5 FIG. 4 INVENTOR,

ALFRED N. FISCHER By M; Abborny 5 United States Patent RESONANT REEDRELAY Alfred N. Fischer, Rochester, N.Y., assignor to Sargent &Greenleaf, Inc., Rochester, NY, acorpforation of New York Filed Oct. 22,1959, Ser. No. 848,118 6 Claims. (Cl. 200--90) The present inventionrelates to resonant reed relays.

In mobile radio telephone communication apparatus, forexample, aresonant reed relay structure of the type herein may be used tocondition an individual receiver for operation in response to a signalof .a distinct frequency. tain a reed of paramagnetic material which hasa resonant frequency of vibration in accordance with its physicaldimensions. The reed, which serves as one contact in a circuit, iscaused to vibrate at its resonant frequency in response to a signalhaving a frequency correspondingto the resonant frequency of the reed.

The operating characteristics of a resonant reed relay containing a reedof a certain resonant frequency are determined to a large extent by theinfluence which the permanent magnet, which controls the relay, has onthe reed. Anything which effects this magnetic influence willnecessarily alter the selectivity characteristics of the structure.reduces the flux-density of the permanent magnet field thus adverselyatfecting the operation of the relay. Also, the gradual decay in thestrength of the permanent magnet, and subjecting the relay to shockcauses it to get out of adjustment which alters its operationalcharacteristics.

Resonant relay structures heretofore known were unable to accuratelyovercome or compensate for the above external factors. This limitedtheir use, and rendered them unreliable under certain environmentalconditions.

In some resonant reed relays heretofore known an adjustable shunt isprovided for varying the field of the permanent magnet to adjust theselectivity of the reed structure.

Any resonant relays heretofore known were so constructed, and theindividual components of the assemblies were so formed that structureswhich were designed to operate at lower frequencies, from sixty to fivehundred cycles, for example, were unable to be assembled and adjustedfor use with resonant reeds having a higher natural frequency, from fivehundred cycles to fifteen hundred cycles for example.

One of the objects of the present invention is to provide an improvedresonant reed relay structure which overcomes the disadvantages of theprevious structures.

Another object of this invention is to provide an improved resonant reedrelay structure which permits the accurate calibration of theoperational characteristics of the relay with a minimum of finaladjustment.

Another object of this invention is to provide an improved resonant reedrelay structure which has a permanent magnet field of constant highflux-density.

A further object of this invention is to provide an improved resonantreed relaystructure which permits the rearrangement of parts in theassembly so as to be operable over a wide range of frequencies.

Another object of this invention is to provide an improved resonant reedrelay that employs a single piece ceramic magnet for creating magneticfields of a constant high flux-density.

A further object of this invention is to provide an improved resonantreed relay structure where the casing serves as a return path for theflux of the permanent magnet, thereby serving to further increase theflux-density of the magnet.

For example, an increase in ambient temperature It is well known thatthese relay structures con- A further object of this invention is toprovide an improved resonant reed relay whose operationalcharacteristics may be varied while retaining the same high fluxdensityof the permanent magnet.

A still further object of this invention is to provide a resonant reedrelay structure which has a low internal resonance and which has animproved resilient mounting means for isolating the reed structure fromits supporting chassis.

A still further object of this invention is to provide an improvedresonant reed relay structure which is reliable under all operationalconditions, has a long life, is of simple construction, and inexpensiveto manufacture.

Other objects of this invention will become apparent from thespecification, the drawing, and the appended claims.

In the drawing:

FIG. 1 is a view in elevation with parts broken away showing a resonantreed relay constructed in accordance with one embodiment of thisinvention;

FIG. 2 is a sectional view showing one arrangement of the components ofthe assembled resonant reed relay;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is a sectional view taken on line 4-4 of FIG. 2; and

FIG. 5 is a view in perspective showing the configuration of thepermanent magnet which is used to control the operating characteristicsof the relay.

A. resonant reed relay constructed according to this invention comprisesan outer casing which is insulated from and resiliently supports aninner casing. The internal resonance of the structure itself ismaintained at a very low natural frequency and the transfer ofvibrations from the inner housing to the outer housing is damped orabsorbed by placing resilient vibration-absorbing material at each endof the relay. A base having an elongated vibratory reed attached theretois rigidly supported in the inner casing. A single piece permanentceramic magnet is adjustably positioned in the inner housing. Thismagnet has a central opening through which the reed extends or withwhich the reed is aligned, depending upon the desired operationalcharacteristics of the relay. An electromagnetic coil is positioned inthe inner casing surrounding the reed and adjacent the permanent magnet.Both the coil and the permanent magnet maybe positioned in the innerhousing at any predetermined distance between the free end of the reedand the base in accordance with the frequency and the operationalcharacteristics desired. Mounted on the reed is i a contact which ispositioned to engage a stationary contact that is resiliently mounted ona Wall of the inner casing.

Referring to the drawing, the resonant reed relay structure, generallyreferred to as 10, comprises an elongated rectangular housing 11 whichhas an integrally formed closure 12 at one end. A sheet of Mylarinsulation 14 lines the walls of the housing 11. Mounted in the housing11 and positioned adjacent the closed end 12 is a block of resilientmaterial 13 which may be foam rubber. Closing the other end of thehousing 11 is a rectangular cap 15 which is attached to and hermeticallyseals the housing 11. Mounted adjacent the cap 15 in the housing 11 is ablock 19 which is made of a resilient material similar to the block 13.A plurality of plug-in terminals 17 extend through the cap 15 and intothe block 19. Mounted in the housing 11 and supported between theresilient blocks 13 and 19 is a rectangular inner casing 21 which isslightly smaller than the outer casing 11 so as to be spaced andinsulated therefrom.

A base 25 which is made of a material such as brass is attached in theinner casing 21 and disposed substanspeasae 3 tially flush with one endof the casing 21 to engage the surface of the block 13. A reed 27 isrigidly attached at one end to the base at 28, such as by silversoldering. This reed which in cross-section is of greater width thanthickness, may be made of any suitable material, which has asufiiciently small temperature coefiicient of expansion. As has beenpreviously stated the thickness and length of the reed2'7 determines thenatural frequency of vibration. Theretore, by selecting reeds ofdifferent dimensions different frequencies can be attained.

Mounted in the inner casing 21 adjacent the base 255 is a spool Cit)made of an insulating material and upon which is wound a coil 32. Thespood 3d is substantially rectangular in section and has a substantiallyrectangular opening. 33 located centrally therein and through which thereedZl' may extend. The spool 39' is cemented to the walls of the innercasing 21.

A. permanent magnet 35, which is of generally rectangular shape incross-section butwhich has chamfercd corners 36, is positioned in thecasing 21 surrounding the reed 27. The magnet 35, which is made of wellknown ceramic materials, is of single piece construction, and has acentral rectangular opening 37.

The surface of the magnet 35 is-in contact with the walls of' the casing21, and is magnetized so that opposite :walls 3-8 and 39 of the opening37 of the magnet which are parallel to the wide surfaces of the reed 27are of opposite polarity.

A mounting block it which may be made of an insulating material, such asphenolic resin, is attached, as by cementing, to the inner casing'21'adjacent the foam rubber block 19. A bracket 42 which is bent to extendin the casing 21 toward the reed 2.7, is attached by rivets 44" to themounting block 4%. A wire 4-6 is attached by soldering to the bracket 42and is bent at one end to form a contact '48 and is" connected at itsother end to one ofthe terminals 17'. The contact portion 48 is diethecasing 21 to tune the reed 27 sharply to this frequency.

As the flux of a ceramic magnet, such as 35, has a linear temperaturecoefiicient, and the structure of the relay is such that the permanentmagnet 35 may be longitudinally positioned relative to the reed, theoperational.

spouse to a low frequency, such as 250 cycles for exposed/adjacent but:normally spaced from a contact protuberance 50 on the reed 27. Thecontact 48 is adjust able away from or towards the protuberance 59 ofthe reed 27 in accordance with any desired degree of amplitude of reedvibration by a screw 52 which is-threaded inth'e bracket 42. One end ofthe screw 52 bearsagainst apiece ofjMylar insulationSdQwhich is cementedto the wall of the inner casing 21. Attached to the Mylar insulation 54between the wire 46 and the Mylar 54 is a block of" foam rubber 56 whichserves to cushion the contact 48 when vibrating. An opening 6t in theinner casing 21 is provided so thatthe screw 52 may be adjusted;

The coil 32 is'conneeted in anelectrical circuit by wires 58"whichextend between chambered corners of the magnet"15' and the casing 21 andarev each attached to one terminal 17' to energize the coil -32 inaccordance with the frequency of the calling signals. The reed 27 is setin vibrationwhen the coil 32 is energized at the resonant frequencyof'thereed 27. Soldered to the wall of the inner casing'21 is a Wire 62which is connected'to one of theterminals 17. This wire 62 is adapted tobe so con nectedin a circuit with the terminal 17, to which the wire46is connected, that a circuit is closed each time the protuberance 50makes contact with the contact 48, thus producing a frequency in theoutgoing circuit which cor responds to the operating frequency ofvibration of the reed: The outgoingclosed circuit in the device includesthe reed 27, its base 25 and the inner casing 21.

The/magnet 35, as already stated, is adjustable longitudinally ofthe'casing 21 to compensate for variations in manufacture and fordifferent desired operating characteristics;

Assuming, for example, that a resonant reed relay constructed:according: to this invention is to operate at six hundred cycles, areed, which has anatural frequency of vibration corresponding'tothisfrequency, is attached to the: base 25,. and'the permanent magnetis. adjustedv in ample, the permanent magnet 35 is positioned moreclosely to the base. In the event that the frequency requires thepermanent magnet to be positioned so close to the base that the spool 38is unable to fit between the base 25 and the magnet 35, theelectromagnetic coil may be positioned on the opposite side of thepermanent magnet between the permanent magnet and the free end of thereed.

Thus, it is apparent that the high flux-density of the one piece ceramicmagnet 35 is not decreased for lower frequencies, but that by changingthe position of magnet 35 relative to the base 25, the elfectiveness ofthe flux on the reed can be altered.

Since the ceramic magnet is an insulator, an uninsu lated wire may comein contact with the magnet without impairing the operation of the relay.

Thus, I have provided an improved resonant reed relay which has a reedstructure that is resiliently mounted so as to be effective againstshock, which has an inner casing that serves as the return path for theflux of'a permanent magnet, in which the magnet may be adjustablypositioned for reeds of either low or high frequencies, and which can bereliably adjusted to provide for different desired operationalcharacteristics under different environmental conditions.

While the invention has been described in connection with a specificembodiment thereof, it will be understood e that it is capable offurther modification, andthis appli-' cation is intended to cover anyvariations, uses, or adaptations of the invention following, in general,the principles of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto'which the invention pertains and as may be applied to the essentialfeatures hereinbefore set forth, and as fall within the scope of theinvention or the limits of the appended claims.

' Having thus described my invention, what I'claim is: l. A resonantreed relay, comprising an outer housing,

one end of which has a plurality of electrically conductive prongsextending therefiom, a resilient mount positioned in each end of saidouter housing, at least one of said resilient mounts comprising a blockof vibration absorbing material, an inner housing contained within saidouter housing and engaging one of said resilient mounts at each end tosecure said inner housing'within but spaced from the walls of said outerhousing, a permanent magnet having a central bore therethrough, a basesecured in said inner housing at one end thereof, a reed rigidlyattached at one end to said base and extending longitudinally in saidinner housing and in alignment with the bore of said magnet, said magnetbeing adjustablelongitudinally insaid inner housing to vary theoperational characteristics of said relay, an electromagnetic coilpositioned in said inner housing-.isurrounding.said reed, said coilbeing connected to a pair of said prongs for energizing said coilat thenatural frequency of vibration of said reed to cause said reed tovibrate, a contact protuberance on said reed, and

adjustable fixed contact positioned in said inner housing and adapted tobe engaged by said protuberance during vibration of said reed, a wireconnecting said inner housing to another of said prongs, and meansconnecting said adjustable contact to still another of said prongs forclosing a circuit periodically at the frequency of vibration of" saidreed.

2. A resonant reed relay according to claim 1 wherein said permanentmagnet is made of ceramic material.

3. A resonant reed relay according to claim 1 wherein said bore isrectangular in shape and said reed is made from a flat strip of metal.

4. A resonant reed relay according to claim 1 wherein said permanentmagnet isa single piece ceramic magnet and said bore of the magnet isrectangular in shape.

5. A resonant reed relay, comprising an elongated rectangular outerhousing, one end of said housing having a plurality of electricallyconductive prongs attached thereto, an elongated rectangular innerhousing contained within said outer housing, a resilient rectangularblock positioned in each end of said outer housing and engagingrespective adjacent ends of said inner housing to secure said innerhousing within but spaced from the walls of said outer housing, arectangular base attached in said inner housing at one end thereof, asingle piece ceramic magnet, said magnet having a rectangular bore, anelongated reed rigidly attached at one end to said base and extendinglongitudinally in said inner housing and aligned with said centralrectangular bore, said permanent magnet being in engagement with saidinner housing and adjustable longitudinally in said inner housing tovary the operational characteristics of said relay, a rectangular spoolhaving a central rectangular opening therethrough, said spool beingpositioned in said inner housing adjacent the permanent magnet andsurrounding said reed, a coil wound on said spool being connected to apair of said prongs for energizing said coil to cause said reed tovibrate, a protuberance on said reed, a fixed contact positioned in saidinner housing and normally spaced from said reed protuberance, a wireconnecting said inner housing to another of said prongs, and meansconnecting said fixed contact to still another of said prongs to close acircuit during vibration of said reed.

6. A resonant reed relay comprising an outer housing closed at bothends, an electrically-conductive inner tubular housing, resilient mountsinterposed between each end of said inner housing and the correspondingend of the 7 outer housing, said inner housing being supported from saidouter housing on said mounts, at least one of said mounts comprising ablock of vibration absorbing material, means insulating said innerhousing from said outer housing, a metallic base secured in said innerhousing in engagement with said resilient block and closing one end ofinner housin an insulating block closing the other end of said innerhousing and mounted adjacent the other resilient mount, a vibratoryreed, which is of greater width than thickness, secured at one end tosaid base, an insulating spool positioned in said inner housing tosurround said reed and having an electromagnetic coil wound thereon, abored permanent block magnet also positioned in said inner housing withits bore aligned with the bore of said spool so that said reed may passthrough its bore, said magnet having a bore which is rectangular incrosssection and being magnetized so that the two side opposite walls ofits bore which are parallel to the wide surfaces of the reed are ofopposite polarity, a fixed contact secured to said insulating block inposition to be engaged by said reed as it vibrates, means for connectingsaid reed and fixed contact in an electric circuit when said reed makescontact with said fixed contact, and means for connecting said coil inan electric circuit.

References Cited in the file of this patent UNITED STATES PATENTS2,758,173 Riley Aug. 7, 1956 2,789,177 Brockway Apr. 16, 1957 2,848,579Russell Aug. 19, 1958 2,866,028 Russell Dec. 23, 1958 2,894,094 HowellJuly 7, 1959 2,922,859 Howell Ian. 26, 1960 2,960,585 Russell Nov. 15,1960

